I'm not sure there can be a direct comparison. However, we run a Vivaro and a Boxer (for work). For both vehicles we annually have Tax, Insurance, Breakdown cover, Mot and servicing to pay. Then there are incidentals, this year we had to replace the front strut upper mounts on the vivaro - at 35,000 miles! Tyres, brakes etc etc.
We have two bikes. Both front hubs, one a self conversion. Simple sytems, battery, contrller, display, motor, pas. No fancy algorythems or blue tooth connectivity (?) or built in battery, just a bike with a motor on it. This year I've replaced the rear brake pads on mine. No excess drive train wear. Tyres last well (Marathons). No servicing bills or tax etc.
However the bikes can't do the jobs the vans do, the vans can and do transport the bikes when wanted. Apart from a bright yellow jacket, I cycle in 'normal' clothes, mostly for pleasure and some shopping. All bike related servicing etc I can do so costs me just time.
Obviously more expensive bikes with tied in systems will be more expensive to run and the more complex the system the greater the fault liability. Keep it simple - keep it to garden shed engineering and it'll be cheaper.